Telephone system



Dec;- 11, 1928. 1,694,934 G. BABCOCK v TELEPHQNE SYSTEM Filed March ef'leze a Sheets-:Sheet 1 G. BABCOCK TELEPHONE SYSTEM Filed March 6, 1926 3 Sheets-Sheet 2 Patented Dec. 11, 1928.

UNITED STATES PATENT OFFICE.

GAERISON BABCOCK, OF SEATTLE, WASHINGTON. ASSIGNOR T0 AMERICAN TELE- CHRONOMETER COMPANY, OF SEATTLE, WASHINGTON, A CORPORATION OF WASH- INGTON'.

TELEPHONE SYSTEM.

Application filed March My invention relates to telephone systems and more particularly to telephone systems em lo in means for ivin metered service.

The present application is particularly directed to means for providing different rates and the provisions and manner for securing different rates particularly in a system in which the service is metered by periodic reversals of current, although it is to be understood that the invention may be employed wherever and in any manner desired.

Where a call has been recorded on the meter at the same rate, regardless of the time at which the call is made, the charge to the subscriber being based on the number of units metered, he has paid for calls at off peak load periods at the same rate as for calls during peak load or busy periods.

This discourages unnecessary calls and calls of unnecessary duration during peak load eriods, which is desirable, and it is the obect of my present invention to avoid any possible objection as discouraging social intercourse or visiting during the less busy periods.

According to my present invention I pro vide means for automatically changing the rate of reversals of polarity so that, for example, during the peak or busy load periods, say from 8 a. In. to 8 p. m., reversals of polarity on the calling line occur more frequently than during the remainder of the 24 hours. I

The frequency of the reversal of polarity is decreased by changing the time interval of pole changer reversal. To do this I eliminate some, for example, every other one of the impulses to the relays controlling the solenoids and pole changers, so that only the impulses not eliminated reach the carbon contact relays controlling the solenoids and pole changer.

I also'provide a multi-zone rate control with means for metering or charging at differcut rates in different zones or parts of the system and means for changing the rates in the ditlerent zones so that night or reduced rate service may be provided in any zone, as desired.

I provide means for delaying the circuit switching without interrupting the passage of the impulses from the clock contacts, for example 15 seconds or 30 seconds, according to the position of the control relay, whether closed or open, to the carbon contact relays controlling the solenoids of the pole changer,

6, 1926. Serial No. 92,768.

and by means of my present invention one time clock or other time control is adapted for controlling more than one time interval. I also provide for testing the solenoid controlling relay circuits and I make certain other provisions which will hereinafter appear.

In order to explain more fully to those skilled in the art how to construct and prac tice my invention, I shall now describe the same in connection with the accompanying drawings.

In the drawings Figs. 1 and 2 are parts of a diagrammatic illustration of a telephone system embodying my invention 1 and 2 are to be laid beside each other with Fig. 1 to the left and Fig. 2 to the right).

Fig. 3 is a detail View of the time control; and

Fig. 4 is a diagrammatic illustration of another telephone system embodying the invention.

As illustrated in Figs. 1 and 2, the system in connection with which I have illustrated a particular embodiment of my present invention, comprises the calling station A, called station B, and a connecting circuit C, located at a central switchboard.

At the subscribers stations A and B, I have illustrated in conjunction with the usual tele phone apparatus, call registering devices 1 and 1, respectively, adapted to be operated by reversals of current. The particular meter or call registering device illustrated is described in my co-pending application, Serial No. 508,037, filed October 15, 1921. Any other suitable metering device ope 'ating upon reversals of current may be employed.

The meter described in my above referred to application is characterized by the use of two series coils connected in the two sides of the talking line and provided with suitable polarizing means and counter-actuating mechanism, whereby a complete cycle of the reversal of current is required for the actuation of the counting mechanism.

The calling station A comprises the usual transmitter 2, receiver 3, induction coil 4, hook switch 5, and ringer or call hell 6. The station is connected to suitable terminals at central over the line wires 7 and 8, which line wires are provided with connections to a cen tral battery 10, for supplying normal polarity of current over the line. The line is provided at central with a suitable answering jack it and multiple jacks, such as 12, connected through a suitable cutoff relay 13. in a manner it iii-own in the art. The line to station ii provioed with a suitable line signal iifor sirialling or indicating to re op 1 l erator at the er'chan 'e that a conn tion l sired. T al is controlled or governed by a line relay 15.

The coinuuinn cor. the central operator i answeringplug cooper-it n1 wit oii n l 1 ta l- I V 1 also t'OlllltClt'tl to a serves to encrs the called line and the s eeve cia :iiridcd with ri 1 i Oil :Or (,Olllltltk While have ill. c circuit in the par icular embodiment of my present invention which I 1 describe. it is to be understood that the invention is not limited in any manner to embodiment in a 3-strand cord circuit and that my illustration of the same is for the purpose of clearly showing" the invention in as simple a manner as possible.

One end of the cord circuit C is supplied with battery from the central source 1-1) over suitable connections which will be .c later. These connections include the answering supervisory relay 31, which, in connection with the sleeve rela' 9L contril. supervisory signal *2. In a similar 1 d scribed nai-ner. batterv is fed to the ringing end of the cord circuitl rom the central source 10 over suitable connections. in this case wire 33-, winding 234iand conductor 35 to the tip strand and from the other side of the bat crv, over wire 36, winding 37 the St'lPOl'YifOlf' relav 3S, conductor 39, to the ring or sleeve strand 26 ot the ringing" end of the cord cir lively, through the supciw'isory i 1'GSlSi1t1FCQ' own arc of tl c aces R and ll d together and actuated to is con- "'tances ctors i5, and The upper end of the (1-1 conihi cl v.

The lower ends and R are 'onncctcd "e iehninal of the bt ry 10 my :znccs ll. ll. he no diherein'c of I -l-iand 48, it the iv, T1 are simu taneously cointo reduce the (illtlCt 'ilie same, fl

ii will cxhihit a acre positive Y El. while the terminal 48 will exhibit ne ative potential. In other words,

1 *nces R R are simultaneousssed, a current flow will be set out cl 11g strands as follows: from hrough conductors 45 and 50, resistance R and out through the line by way of the conductor 52 and the terminal &8, bacl: from the line throu h tcrn'iinal l7, conductor 5%. resi; ance R and to battery 10 by ray of conduccors 55 and 4 .6.

It, now, the pressure on the resistances R and R is relaxed or rel lied and simultaneously the pressure on the resistances R and R" is increased, the terminal t? will exhibit a strong negative potential, while the terminal 48 will exhibit a strongpositive potential. \Vhcn the res'stunceis R". it are simultaneously compres ed. the current flow out through the talkin v.t and is as follows:

conductors L5, 51, resistance R, conductorsv and 54: out through the line by wa at the terminal 1-7, and back through the conductors 52 and 5S, resistance 11 and conductors 5G and i6 tc battery.

To enable the attendant to obscri'c any out of balance conditions in the rhcostaii-u a balance indicator (a) may he pl'GYl-li'ftl l: tween the line teedv and the battery. \Vhcu resistances R R, are simultanei uslv compressed, a flow of current is set up from battery 10, through the conductor 62 and the coil 61 of the indicator G0, which is now in parallel with the resistance R out through the line by way of conductor and bael; from the line through the coil (3t oil the in l iter, which is now pa 'allel with the reance R to batter, by way of the conduc tors 65 and (S6. Vhen the re stances It", Ff are sinniltaneouslv compresset a low oi the outgoing current will be set up through lit) R and the coil 64 back to battery, while a flow will be set up through the coil 61, resistance It and back to battery. In this case the indicator coil 61 is connected in a local circuit in series with R and the indicator coil 64 is connected in series with resistance R. In the first. instance, the voltage impressed upon the coil 61 is dependent upon the I R drop across the resistance R and the flow through the coil 64 is similarly dependent upon the I R drop across the resistance R In the second instance, the flow through the coils 61 and 64 will be dependent upon the respective values of the resistances R and R, which are connected in series with said coils 61 and 64, respectively. In either case, any out of balance condition will be indicated so that it may be corrected.

The arrangement for actuating or compressing the pairs of resistances, comprises a pressure cylinder 73 for the rheostats R, R and a pressure cylinder 74 for the rheostats R, R. Piston rods 75 and 76 connected at their inner ends to suitable pistons within the cylinders 73 and 74, respectively, are adjustably connected at 77 and 78 with rheostat actuating shoes 79 and 80. Actuation of the respective rheostats is had by engagement of these actuating shoes with the insulated buttons 81 thereof. The supply of compressed air or other suitable motive fluid from the common intake 82 to the cylinders 73 and 74 is regulated by suitable adjustable pressure regulators or pressure reducing valves 83 and 84. The conduit 82 may communicate with any suitable source'of pressure. The conduits 86 and 87 provide exhaust outlets for exhausting the pressure from the chambers 7 3 and 74, while suitable valve members 88 and 89 control the flow to and exhaust from the respective pressure chambers. The pressure chambers 74 and 73 may be provided with suitable pressure gauges 90 and 91, respec tively.

The blocks 77 and 78 through which the rods 75 and 7 6 are connected to the actuating shoes 79 and may be adjustable along the respective shoes so that any out of balance condition in the rheostats may be quickly and conveniently adjusted by moving the block along the actuated shocs to the desired position. The actuation of one pair of resistances relative the other may be varied by regulating the pressure admitted to the chambers 7 3 and 74 by means of the regulators 83 and 84 and the degree of actuation of anyresistance rela tive the other resistance of the same set may be adjusted through the connections 77 and 78.

The actuating arms 92 and 93 for controlling the valves 88 and 89, respectively, are connected at their free ends to the opposite ends of a link 94, which link is connected by a pin joint at its center to the upper end of an actuating lever 95. A pair of bridging contact lingers 96 and 97 carried by the opposite end of the bar 95, are adapted for bridging terminals 98, 99 and 100, 101 of a valve controlling circuit. The lever 95 is pivotally mounted centrally and is rigidly joined to a cross bar 102. The cross bar 102 is connected at its opposite ends through suitable links 103, 104 with the plungersor cores 105, 106 of a pair of solenoid windings 107, 108. The terminals 99 and 101 are grounded at 109. The circuits through the solenoid windings 107 and 108 are controlled by apair of time controlled relays 110 and 111. The windings of the relays 110 and 111 are connected at one end to a battery or other suitable source 112, which source is grounded at 113.

The circuits through the relays 110 and 111 are controlled by a time controlled circuit controller which operates to automatically energize the relays 110 and 111 at difierent intervals or periods at different times of the day to meter the service over the calling line at different rates at different times, for example, at a higher rate during the on top peak or during the loaded or busier part of the day, and at a lower rate during the off peak periods or before and after the busier parts of the day.

The time controlled circuit controller comprises a two throw cam 117 mounted, for example, upon the second shaft of a suitable clock and two pairs of cam contacts 114 and 115 which are alternately closed by engage ment of the diametrically opposite cam portions of the wheel 117 with the cam trips on the contact springs or arms. The two throw cam 117 completes a rotation every 60 seconds, which means that the horizontal contacts 114 above the cam are closed every thirty seconds and, likewise, the vertical contact springs 115 to the right hand side of the cam are closed every thirty seconds, the vertical contacts 115 being substantially clockwise from the horizontal contacts 114 and the closing of the vertical contacts oc curring fifteen seconds after the closing of the horizontal contacts.

The impulse or closing of the contacts 114 (about one-half second) energizes the carbon contact relay 120 and similarly the impulse of the contacts 115 energizes the contact relay 121. Energization of the relay 120 actuates the armature 122 to close the contacts 123 and thereby complete the circuit from battery 112, through the winding of the relay 110 and by way of conductor 124 to ground at 125. Similarly, energization of the relay 121 actuates the armature 126 to close the contacts 127 and thereby complete the circuit from battery 112 through the winding of the relay 111 and by way of conductor 128 to ground at 129.

Energization of the winding 107 causes movement of the plunger 105 inwardly, thereby swinging the bar about its pivot to admit pressure J one of the tf 'lindeixs for example cy iider 3, and exhaust the other cylinder T theresy compressing the resistzinces R i1 and releasing the pressure upon the resistances i i This inor ment of the bar moves the CO1 tact 96 out of engagement with the contacts 98 and 90 one the contact 9?, and the contact 9? into engagement i'ith the cents 100 and 101, selecting the circuit through the \in tin 103 which cirf s 1 l act: h co n ccrit 1, close at 11!; cent s J a a men; of the cam \YllCQl 117 with the contacts 115. The circuit through the Windino' 10? is closed by engagement of the coin whee 11? with the contacts 11-, s will be explained. Completion of the circuit through the wind ing 108 swings the bar 95 in the pposite direction to compress the other 172111 of resistsnccs 1i, and selects the (fll'CLlt through the 'inding 1O?- The windings of th 'ehi 121) and 121, are nlterinitel COllllGCt it across :1 battery or other suitable source 150. Inter-posed in circuitwith the relay 120 is n so-czilled distributing switch 151 and similarly interposed in circuit with the relay 120 is a siinihrr distributing switch 152.

The purpose or toe switc is to change the time interval of o rei'ersal by changin the mini e; i

tions of the relays 120 and 121 i tation of the time controlleC- switch 151 comprises a grow connected by cont nctor o group 01 contzi relative connected by e. conductor 1oz. doctor 1535 is connected by s c to the winding 01 the relay 1%, end 01' which Winding is connecte ductor to the winding the Witl 21 conductor 1G2 conneting' t tor 1450 with one side of c opposite side of th hatter]! 1Z0 is connec "ed i Ste H 1 i Z. tire nutter e 1 through contacts 111 when said contacts are closed by the earn 117 with a cord to; r 161- connectcd to o cordiictingr or contact nrin 1135 pivoted at d nnwoble succe sii'elv into ergng'enient i'i l e 156 to tv connect them and The tiistrilniting the switch 151 out \Yll'ttl contacts, tl

desii 1 reference meruis' cor 'esponding to tiiose of the 1:31. The conductor 15 being:

tracts 1: 1 of the SM lLCll. is connem throu ih the relay 121 and conduc ors 160 and V r. .1: n it A 162 to o. 0 sh m roe nitteiv 1-10 and the 11 other side of the hatter 150 is connected through the contacts 115 and conductor to th contact a in The conductor 15. of thswitch 1 connected by a conductor 17' with a co 1T6 of switch 17'? and the cooperating con- :1 con connectr z is contro e circtii 1 4h ry 150 thro rn a conn' rough relay 1.13 and the Y c ock contncts and a conductor is in c i LOJ J cooper-r11 do sioe oi the battery. En-

he rehiy by closing the r" lll\")l .f {ll during the oil? me; of the day, uctuzrtos open the ccntc LS o1 the circuits of the distributor seconds to 3 1 .inzit is, the ot' reversals YGD time is decreased to 1G rate oi regirnrzmon upon the theieb the rate of chr 13 during otiho day, that is when time that the r purpose of the :{Eihn'alii or (hire- 1 be varied, oi ireinents. contort time cvm'v Ell one side of t swit 11 ahead of said and the onoosite side or the battery 150. The relay 195 has an armature 197 pivoted at 198 and connected with apawl 199 which cooperates with a ratchet 200 attached to the contact arm 165 to advance the arm from one of the contacts 154, 156, to the next contact 154, 156 by the back-acting movement of the armature 197, which movement is imposed by a spring 201. The back action of the armature 197 by the spring 201 thereby advances the arm 165 one contact and the movement ofthe armature 197 under the influence of the relay 195 when said relay 195 is energized, moves the pawl. 199 to take over the next tooth of the ratchet so that the contact arm will be advanced another contact with the next back action of the armature.

The action of the relay 196 and its armature 197 is the same when the other circuit is closed through the contacts 115.

Each of the distributing switches 151. and 152 may be provided with a hand switch 210 and 212, respectively. These switches are useful for test purposes in regular operation. Normally they stand open, and by closing them the switch 177 may be shunted out of circuit for test purposes, as desired.

To assist in adjustment of the various resistances or rheostats, an arrangement for indicating to the attendant the performance or operation of any of the individual rheostats is provided. This includes a suitable voltmeter 215, a selecting switch 216 for connecting either of the resistances R R R or R individually thereacross, and the necessary circuit connections therebetwen.

I shall now describe briefly the operation of the particular system of Figs. 1 and. Assuming that the subscriber A desires to be connected to the subscriber B, the receiver 3 is raised, thereby completing a circuit from the battery 10 as follows:

Battery 10, conductor 62, 130 and 131, line relay 15, line wire 8, through the instrument and meter at the station and back through line wire 7, conductors 132, 133, 66 and 4L6 to battery 10. Since the meter requires a complete cycle of current reversal, it-

not now actuated. Line relay 15 being thus energized closes a circuitfrom battery through. line signal 14, indicating to the operator at the exchange that a connection is desired. The operator thereupon makes connection with the answering plug 16, effacing the line signal and connecting the strands 18 and 19 to the line wires 7 and 8. Current of the prevailing polarity thereuponflows out over the talking strands 18 and 19. and over the line wires 7 and 8 and supplies current. to the instrument at the sub-station A. The operator, through the medium of the listening key 22, communicates with the subscriber and receives the order for the desired connection, and assuming that the subscriber B is desired, selects and tests the terminals of said line and proceeds to make the connection. The ringing key 29 is actuated to project ringing current over the called line, and when the party B answers, current flows in normal direction over the line of the called party, and conversation between. the parties may be carried on.

The time controlled cam 117 rotates continuously, successively closing the contacts 114 and 115 and thereby the circuit through the solenoid windings 107 and 108. The closing of these circuits is only momentary, sufficient to operate the valves 88 and 89, for example, and set the connecting piece or bridge carried by the bar 95 for closing the other circuit. The operation of the valves 88 and 89 in turn controls release of one set of resistances and compression of the other set. A complete cycle of change of polarity occurring in the calling line from positive to negative and back to positive, or vice versa, causes an actuation or registration upon the meter 1 at the calling station.

During the less busy or off peak periods of the day when the time controlled contact arm 187 comes into contact with the contact element 188, the relay 185 is energized and opens both branches of the switch 177 so that every other impulse of the carbon contact relays which actuate the solenoids are elimiated, the reversal of polarity being thereupon only one-half as frequent and the rate of registration upon the meter being only one-half as great as during the busier pe 'iods when the switch 177 is closed and each of the successive contacts of the distributing switches 151 and 152 act to transmit an encrgizing impulse to the rheostat solenoids.

It is to be understood, of course, that the motor coils of the backer-ting distributing switches may be in series with the motor coils of the pole changer control relays; also, that a connnon source or battery may be employed for the entire system and that other variations and circuit connections are contemplated.

The s lowing of the time controlled contact cam 11.7 and the night or half rate control clock 186 in Fig. 2 is, as already pointed out, diagrammatic for the purpose of imparting a clear understanding of the invention. The Contact cam 1.17 is }')referably on the second hand of the clock 250 with the contact arm 187 mounted on the same clock as shown in Fig. 3 to make a rotation every twenty-four hours, for example. The 011 peak. or night? rate contact is shown at 188, as before, and the clock may be provided with an automatic clock winding motor In Fig. 1 I have shown a inulti-zone rate control system. While the number of zone rates may be varied, the particular system shown has three pairs of relays 260-260, 261261 and 262262', each pair controlling the solenoids of a pole changer as in Figs.

1 ani 2. For example, as laoeled, the relays 260. 260 are connected to the solenoids of pole changer 1, the relays 261. 261 to the solenoids oi pole changer 2 and the relays 262 262 to the solenoids of pole changer 'lhe relays 260. 261 and 262 are controlled by contacts 275, and the relays 260', 261 and 262 by contact 276, which contacts and are controlled by a [ire-second time coir trolled contact closing cam 278.

The circuits of the contacts have a distributing switch 281) and the circuit of th contacts 276 has a distributing switch 28;. The switch 280 has 2 group of enected contacts for each relay 260, 261: 2. the her of contacts in each group he dinerent. so that the number of enera" pulses to each rcla 260, 261 2111i: 7 tion of the cam 278, will vary accoi o1 t to the ditl'erent zones. The pole chan els are connected to the systems or the (hi i t and the rate of metering or charge in ea ch zone is diii'erent because of the 'dili'erei t number of impulses per rotation to relays 261 and 262, (littering according to the particnlar ate of impulses in the particular 1e oi the calling party.

The distributing switch 280 has a backacting relay 285 for advancing t contact arm 286 over the contacts or t serc 'al groups to connect the central contact piece 287 successively therewith. The switch 2? has a similar relay 290 for the same purpose. The battery or other source is indicated at 292. and an outer group of connected or i ired contacts of each switch W0 and 282- is connected to the battery through a suitable resistance.

In operation when contacts 2'75, for example, are closed the relay 260 261 or 262 connected With the contacts or the switch 280 with which the contact arm 286 is in engage ment. is energized and the relays 280 .2=3l and 262 are similarly energized to cor. lete the C '\'Cl oi reversal.

w 1 :12 i or L 1e puipo e or pronoun; a rein or h iii ate 111 cc: n nction with the mul i'ates,Il1:-1'\'e shown a switch 2.92 cone l'\'6011 the switch 202 and the relay 2 an provided with two groin s of contacts 293 5111i: 29% with a heel lQlil) 295 or adrane ing the contact )6 over the contacts 293 and and a switch 29? for ccnnccting the rela into and out of circuit. The cont- 2 coin ay or t ne conn disconnectt lhiltl ldur their: more than one time 'nterval For instance a clock with live second c will serve our number of pole change" the n nltiple of tire seco claim In combination,

telephone set. a called line having a telephone set, a cenncct'ng circuit for interconnectin; the lines for telephonic communication, lnean for reversing the polarit'; of current lines a single re reversals ot' (illzflCDti'or register rrals over the talking" line, using said intervals durin corn "o i, a calling ine having a t ci'iri'ent. a

meter ojerated by reversals o called line a connecting circniti ire-1m! lines. \illtl lklitj :ZLLIlL" ill ltllli iUi, lflltlalnil ill! I it hit or current over the c: llingr line, cl

. a i I tic-Jr l is: cont-illine said 1) .ig mean. ime unfilled. means groti'he actual'iiilgi or" said clcc'roinzumctic mean. and means for chantgiir he clicct of said time controllcd mans on raid electroniagrnec means to chance the rate of oola rerc s over the calling line a nip; rate "for the SOLYlCC over st EC 3. In comhination, a aria esistancc pcie change a rela controlling said po 0 changer. a distributing switch controllingsaid rel: 3., a second rehy for operating raid switch. and timing means controlling said econd relay.

nuans for in'ipartine to sa 1 e rea a telephone line and means 'rcr elin i rations of said rela tween energizatio' a tuln conibi havi g; a plnieniber mom bie therewith, t me cor ing said. switch me means for de-encrgizi 1 said switch.

T x I l. in come V i a ca ew a connec ma circuit to "*L'COHI'ROW' conntninica.

lh es "for telephonic operated h -i reversals cit polar" ur cut for mcasuring tie service over the alling line means in the ctnnectine circuit Jr reversing the polarity of c1 tnt over .cid line, electromagnetic means controlling aid polarity reversing means a icia con trolling said electromagnetic means a diserine' device tributing switch for imparting successive energizations to said relay, a timing device for said switch, and time controlled means for eliminating alternate energizations of said relay to decrease the rate of polarity reversals over the line.

8. In combination, a calling line, a cal ed line, a connecting circuit :for interconnecting said lines for telephonic communicatioi'i, means operated by reversals of polarity of current for measuring the service over the ialliug line, means in the connecting circuit for revcrsin g the polarity of current over said line, electromagnetic means controlling said polarity reversing means, a relay controlling said clezttron'iagnetic means, a distributing switch for imparting successive energiyations to said relay, said switch having a plurality of contacts, a timing device for said switch, and time controlled means for de-energiziug alternate contacts of said switch to decrease the rate of polarity reversals over the line.

9. In combination, a telephone line, a circuit connected to said line and including a pair of variable resistances, means for automatically alternately increasing one resist ance with respectto the other to reverse the current over said line, a service measuring device operated by the current reversals, and means for changing the rate of operation oi said resistance increasing means to vary the rate of registration upon said service measuring device.

10. In combination, a telephone line, a potentiometer circuit comprising two variable compressible resistances, terminals leading to said telephone line and connected to said potentiometer circuit, means for varying said resistances alternately, and means for changing the rate of operation of said resistance varying means.

11. In combination, a telephone line, a potentiometer circuit comprising two variable compressible resistances, terminals leading to said telephone line and connected to said potentiometer circuit, electron'iagnetic means for varying said resistances alternately, time controlled means governing the actuation of said electromagnetic means, and means for changing the rate of actuation of said electromagnetic means by said time controlled means.

12. In combination, a telephone line, a potentiometer circiut comprising two variable compressible resistances, terminals leading to said telephone line and connected to said potcntiometer circuit, electromagnetic means for varying said resistances alternately to reverse the current over the line, time controlled means governing the actuation of said electromagnetic means, means for changing the rate oi actuation of said electromagnetic means by said time controlled means, and a service measuring device operated by the reversals of current over the line.

13. In combination, a telephone line having a meter actuated by variations of current, a potentiometer circuit for supplying talking current to the line, said circuit including a pair of compressible variable resistances, means for alternately compressing said rcs' tan and means for varying the rate of compr ssion oi? the resistances to vary the rate of operation of the meter.

14-. In combination, a telephone line having a call meter adapted to be operated by reverals of current, means for supplying current to the meter, said means comprising a cord circuit having a pole changing device for supplying current to the talking strands of the cord circuit, said pole changing device comprising a pair of carbon piles adapted to be periodically compressed alternately, and means for varying the rate of compresison of said carbon piles.

15. In a telephone system, a talking line, means "for supplying current periodically in reverse directions over said line, said means comprising potentiometer circuit including a pair of non-interruptible variable resistances, a pair of electromagnets for alternately varying said resistances, a time controlled circuit controller for periodically actuating one of said electromagnets, a polarized circuit changer for determining the electromagnets to be actuated, and means for varying the rate of actuation of said electromagnets by said time controlled circuit controller.

16. In combination, a subscribers line hav ing a subscribers station, non-interruptible means for reversing the polarity of current over said line, a service measuring device at the subscribers station and operated directly by the reversals of current, said service measuring device dividing the talking interval into a number of units each separated from the succeeding unit by reversal of current over the line, and means for changing the rate of current reversals to directly change the rate of registration upon said measuring device at the subscribers station.

In Witness whereof, I hereunto subscribe my name this 27th day of February, 1926.

GARRISON BABCOCK.

Inn 

